This invention relates to a magnification adjusting mechanism for moving an optical system to allow a copying machine or the like to change its magnification to less than 100%, 100% or more than 100%.
Heretofore, in copying an original at a magnification of more than 100% or less than 100% with a copying machine, first a magnification setting key on the operating panel of the copying machine is operated to set the magnification to a desired value, for instance 150%, and then a print key is depressed. When, in this operation, the magnification setting key is operated, immediately the optical system including lenses, mirrors, etc. is moved to a 150% magnification position to copy the original at the magnification of 150% thus set.
In a copying machine of the type that an original's size is automatically detected, its optical system is operated as follows: When an original document is placed on its contact glass plate, or when an original document cover is closed thereafter, the size of the original is automatically detected. A magnification to be used is automatically calculated from the size of the original document thus detected and the kind of a sheet supplying cassette selected, then the optical system is moved to a position corresponding to that calculated magnification.
Even if the magnification is set in this way, it is not always correct and sometimes it is necessary to further modify the magnification.
The conventional copying machine is designed so that when the magnification is set, by magnification inputting keys or by placing the original document on the contact glass plate or by closing the original document cover, the optical system is immediately moved to the position corresponding to the magnification determined. If there is a large distance between the current position and the target position of the optical system or the magnification needs to be modified, then the copying operation requires a lot of preparatory time.